Researchers who have analysed the hierarchical categorisation of life on Earth to estimate how many undiscovered species exist say the diversity of life is not equally divided between land and ocean. Three-quarters of the 8.7m species - the majority of which are insects - are on land; only one-quarter, 2.2m, are in the deep, even though 70% of the Earth's surface is water.

An astonishing 86% of all plants and animals on land and 91% of those in the seas have yet to be named and catalogued, the study said.

Biologists have long known that insects make up the vast bulk of the planet's biodiversity -- a previous estimate held that there were up to 30 million different insect species in the rainforest alone. And they've been working on pinning down that magic number for decades. The first-ever estimate, made by the pioneering taxonimist Carl Linneaus 250 years ago, clocked in at 10,000.

The Guardian also spoke to Dr. Camilo Mora of the University of Hawaii and Dalhousie University in Halifax, Nova Scotia, who said that this quest is growing increasingly urgent: "Scientists have been working on this question of how many species for so many years. We know we are losing species because of human activity, but we can't really appreciate the magnitude of species lost until we know what species are there."

Indeed: if you're a regular Treehugger reader (or follower of conservation issues), then you're well aware that some biologists already believe we're in the middle of the "sixth extinction". This one, of course, isn't caused by a meteor strike or a major flood basalt event -- it's caused by human beings, who happen to be fully cognizant of the damage they're doing to the natural world! Some scientists say that we're currently causing species to go extinct at 10,000 times the background extinction rate -- which makes it hard indeed to get a firm head count of those still standing.

But look on the bright side: If we continue to destroy our natural environs at such a prodigious rate, we may soon be able to get an accurate tally of how many species there really are in the wild. We'll wait to count 'em on two hands if we've got to!

Photo credit: NASA Goddard Institute of Space Studies
... According to the latest study
Scientists have just completed the most accurate tally of the planet's species yet (though the projection still has a pretty healthy margin of error). The magic